This invention relates to the surface treatment of a body of material presenting a planar surface to modify said surface to produce an interface layer of finite depth which provides for entry of another material into the interface layer and within which interface layer material extends from said body and presents an extended surface area.
In the context of this specification, xe2x80x98planarxe2x80x99 refers to the local character of the surface, and does not exclude for example surfaces which are smoothly curved or cylindrical.
In Canadian Patent No. 1,330,521, issued Jul. 5, 1994 and assigned to the present applicant, there is described a surface treatment applicable to freely machinable material in which a pattern of planing cuts is applied to the surface of a material to provide an array of retroverted non-detached shavings or burrs which provide such a layer. This layer can be penetrated by another layer, for example a fluid which may be liquid (for example a melted or curable material which thereafter solidifies) or gaseous, or another similar formed surface layer on another body of material. Formation of such a layer requires repeated reciprocatory applications of a cutting edge of an appropriately formed tool or tools, which means that provision must be made for maintaining the cutting edges of the tools, and severely limits production speeds unless the number of cutting edges is very large.
It is an object of the present invention to provide an alternative method of producing such an interface layer, and to provide materials having such an interface layer of different configuration.
According to the invention there is provided a method for preparing a surface of a workpiece of solid ductile material to provide a transition zone between that material and a different material to be brought into intimate contact with the first material, comprising relatively moving a contact zone between said material surface and a substrate to which are bonded adhesive particles much harder than said material while pressing said particles of abrasive into said material surface, such that the abrasive particles score recesses extending longitudinally in said material surface while displacing said ductile material from the scores into processes integral with said material and extending outwardly from said surface and parallel to said scored recesses into spaces between the material surface and the substrate, said recesses and processes together providing a transition zone between said ductile material and the different material.
Typically, the substrate is a belt or drum, and the size of the particles, their distribution on the substrate, and the relative speed of the material surface and the substrate, are selected so as to avoid substantial stripping of the processes from the surface by the abrasive particles. Greater irregularity of the processes may be obtained by varying the relative speed of the material and the substrate during operation, and/or varying the spacing between the material surface and the substrate. The depth of the interface layer from the bottom of the scores to the outer extremities of the processes may be further controlled by lightly rolling or brushing the treated surface of the material. Preferably the spacing between the material and the substrate in the contact pressure zone at least equals the depth of penetration of the material.